Wood pellets or oil, ufh or rads

[CK11]

It's almost time to decide on heating for our new build, no mains gas!
The house will be approx 475sqm , average insulation but no where near passive levels
Approx 125mm floor, cavity block walls 100mm xtratherm, 300-400mm in the attic
Will be trying to make as airtight as possible with 3 small kids running in and out.
Walls insulation were already fitted and we only can fit 125mm in the floor or I would have specified more
We seem to have narrowed it down to either a wood pellet boiler to avail of the the 7 year rhi payback or good old oil
Ruled out gshp due to costs and a friend who installed one and doesn't rate it at all

Any thoughts or recommendations appreciated

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clockworks said:

I'd go for oil for a wet heating system. No idea how much wood pellets cost compared to oil, but plenty of oil suppliers in this area, never seen a wood pellet truck?

In a new build, I'd seriously consider electric, as it's unlikely to run out. I had storage heaters in my last house, with the unit in the lounge being an underfloor element buried in a large concrete slab. Not that expensive to run on Economy 7, and pretty much zero maintenance.
Back it up with a multifuel stove.

Pellets are about £210 a tonne blown into a hopper, oil currently dropping. Approx 47p per litre
The rhi for pellets is a big draw , approx £1500 give or take a few hundred quid a year payback, basically free heat for 7 years. Do have access to quite a bit of wood

So many variables out there it's a minefield

[CK11]

A few posts and everyone with basically a different opinion
This is my trouble, there doesn't seem to be a general consensus on which option to go for
It's probably going to be financially the biggest outlay on the property and I really want to get it right
Oil, pellets, Ashp, gshp, log burner with back boiler

How about ufh or rads? Another thing I don't want to make a mistake on
Think we have decided on rads upstairs, it's just downstairs with about I think 250-270 sqm to cover
Always had rads and like the idea of fast heat on the other hand ufh gives a better feel and apparently is more efficient
But needs to be on for longer periods of time than rads albeit at a lower heat

[CK11]

Getting more confused by the post

[CK11]

Is that 3 x 25kg bags per day in the winter months!

[CK11]

Yes as long as it's in the rhi scheme list of approved stoves and fitted by an approved mcs installer

[CK11]

Could you give a little background as to your property and which make model pellet boiler you use?
How many ton per year of pellets?
Did you qualify for rhi?
Do you also use a separate wood burner?

[CK11]

Can I safely say I the grants were not available oil would win when not on mains gas
With the grants in place currently pellets. Win

Can the government stop the grants at any time they wish , ie install a pellet boiler at circa 10-12k and get the rhi payments
And in 6 months or whatever they can say we are no longer paying out and the scheme is over, even for existing customers or do they have to guarantee the 7 year payments

Is there a multi log and pellet boiler on this scheme?

[CK11]

As far as I am aware the broseley evolution 26 boiler stove is the only log burner currently on the green deal scheme, could be wrong on that though.
I do like the idea of a combined log and pellet stove, cant seem to find a lot of information on them though

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For those running UFH, do you leave it on 24/7 and setback to say 16oC then the thermostat fires up the boiler until say 20oC, or do you have it set on a timer or switch it on as needed?
What thickness of screed for a wet system and how long to heat up from say 16 to 20oC

Wife nagging me to fit rads and says ufh will cost a fortune to run, I don't want to make a massive mistake and get a 'told you s'o everyday for the next 25 years

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RedLeicester said:

UFH is way cheaper than rads to run, all the more so with renewables, dunno where she got that idea from. In order to run rads you need hot water up to around 70 degrees to make them hot enough to exude useful heat. For UFH that drops to 35-40. UFH is more expensive to install, but cheaper to run, vice versa for rads. We've put UFH throughout downstairs and left the rads upstairs for phase two. As it is I wish we'd just done the lot as the punch in the logwallet when the rads kick in is painful.

Warm up time depends on how cold the slab is and how big it is. Screed thickness depends on type of UFH used and how it's installed.

Ours is all zoned and controlled using Heatmiser thermostats - it "learns" the warm up time for the room so drops a few degrees off overnight and then kicks in in time to be up to temp at your desired time. Ours isn't on 24/7 so much as 365 - it's just constantly ready to go as and when thermostats demand.

Heatmiser is what we have been quoted for also, each room its own thermostat etc
Surprised to hear you say you wish you had UFH in the bedrooms, 90% of people seem to say Rads are better and more controllable for sleeping temps. Sand/cement screed seems to in the 70mm region, wet you can go down to 40mm btu a lot more expensive and problems then with tiling etc

I guess its the old argument that when someone thinks the heating is on 24/7, when its really not, its going to be a lot more expensive than switching the heating on for a couple of hours here and there in the morning and evening. I guess it also depends on how airtight the house is, how well it holds the heat if your out say 9-5. A lot of peoples thinking is what is the point in having heat running when no one is home.

[CK11]

4 Pages in and still non the wiser even though better informed!

[CK11]

Making oil very attractive at the moment for sure

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jason61c said:

Awesome, just had this confirmed too The best £150 I've spent. Ever!

I'm currently doing some walls in lime hemp at the minute, its good stuff but does take an age to dry. I do plan on putting something breathable on the inside like yourself on the exposed walls.

Just waiting on some people coming round to give fixed quotes, looking at Froling/Effecta/hoval/ETA. I'd like something that will outlast the 7 year RHI.

I'm quite excited

Any decisions made yet?

[CK11]

Good luck with it, let us know how it fairs out
How many kW? What size is your house?